Evaluation of Insecticidal activity of selected medicinal plants against Tetranychus urticae (Mites)

Abstract

Aqueous extract of some selected medicinal plants Allium sativum, Zingiber officinale, Capsicum annuum and Azadirachta indica were evaluated for their insecticidal activity against on two spotted mites Tetranychus urticae, which is a pest that causes serious damage to several plants. Propargite was used as a standard for insecticidal activity and percentage mortality was found to be 100%. All individual extracts exhibited concentration and time dependent insecticidal activity. The formulation consists of equal ratio of extracts of Allium sativum, Zingiber officinale, Capsicum annuum and Azadirachta indica showed a high toxicological effect, producing 90% mortality after 72 hours. Results clearly indicates that the formulation of Allium sativum, Zingiber officinale, Capsicum annuum and Azadirachta indica can be used as an effective agent for the control of two spotted mites Tetranychus urticae and it could be tested against other pest affecting crops throughout the world there by reducing use of synthetic pesticides

Keywords

Natural insecticide; medicinal plants; Allium sativum; Zingiber officinale; Capsicum annuum; Azadirachta indica

Introduction

The two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae), is a generalist herbivore that feeds on many crop and ornamental plants. Hot, dry weather is conducive to spider mite outbreaks. Damage can be seen as chlorosis of the leaves where the mites have been feeding. Its short life cycle and high reproductive potential predispose this mite to evolving resistance to many chemical control methods ^[1]. 

Their colour is generally pale yellow or orange with no spots. Eggs are round, almost clear, about 0.1 mm in diameter, and these may become pale brown just before hatching. Female two spotted mites can lay more than 100 eggs during their lives of approximately 30 days. Eggs hatch into first instar larvae, which are white, oval, and about 0.1 mm long and have six legs. Most spider mites prefer warm and dry conditions, and suitable conditions could speed up the mite’s life cycles ^[2]. The two-spotted mite T. urticae takes 8-12 days at 30°C-32°C to complete its life cycle.

Some spider mites can act as vectors in transmitting plant diseases. The potato virus y, which affects potato, tomato, tobacco, and other Solanaceae, can be transmitted by the two-spotted mite. The mite does not actually inject the virus into the plant, instead excretes the virus into the leaf surface and permits entry of the virus into the plant through feeding damage. The two-spotted mite can also transmit tobacco ring spot virus, tobacco mosaic virus, southern bean mosaic virus, and cotton curliness ^[3].

The neem tree, Azadirachta indica A. Juss is a member of the Mahogany family, Meliaceae. It is a fast growing tree of multipurpose use. One of the important uses of neem is its use as a source of botanical pesticides. As far as its use as a source of insecticides is concerned the main interest of the scientists has focussed on the products derived from neem seed kernels and the pure compound azadirachtin.

Garlic, Allium sativum Linnaeus (Amaryllidaceae), is a native of temperate western Asia and has been used throughout the world as a food spice and medicine. Antimicrobial, cardiovascular, anticancer, hypo- and hyper-glycaemic, and other beneficial properties of garlic have been reported ^[4]. In different studies, garlic essential oil was demonstrated to possess insecticidal activity against Blattella germanica Linnaeus (Blattodea: Blatellidae), Lycoriella ingénue Dufour (Diptera: Sciaridae), Reticulitermes speratus Kolbe (Isoptera: Rhinotermitidae), and several grain storage insects as Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), Sitophilus oryzae Linnaeus, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), and Tribolium castaneum Herbst (Coleoptera: Curculionidae).

Ginger, Zingiber officinale Roscoe (Family: Zingiberaceae) used worldwide as a traditional medicine, has recently been found possessing an insecticidal effect on many insects. Capsicum annum (Family: Capsaicidae), contains capsaicin compound and has many uses as spice and public medicine, as well as its ability to kill certain insects ^[5].

Indiscriminate use of synthetic pesticides for crop production and protection poses poisonous effects through contact, inhalation, and dietary exposure and has become a cause of carcinogenesis, fertility problems and mutagenesis in humans. These circumstances led towards searching for effective and eco-friendly pest control alternatives, especially from natural plant resources. Many insecticides derived from botanical sources are available and are easily affordable and accessible to the farming community; they are safer for human beings and for the environment with minimal residual effect, and they are target-specific and less toxic to vertebrates, pollinators and fish ^[6].

So the current study was planned to investigate the Aqueous extract of some selected medicinal plants Allium sativum, Zingiber officinale, Capsicum annuum and Azadirachta indica were evaluated for their insecticidal activity against on two spotted mites Tetranychus urticae, which is a pest that causes serious damage to several plants.

Materials And Methods

Sample collection and processing

Fresh cloves of Allium sativum, rhizomes of Zingiber officinale and green peppers of Capsicum annuum and leaves of Azadirachta indica were collected from the local market of Coimbatore districts. The samples were rinsed with tap water and then were dried under shade for 2 weeks. The dried samples were powdered using an electrical grinder. 20 g of dry sample powder with 1 L distilled water and heated at 80 ̊C for 20 min on a hot plate ^[7]. The solution was filtered by filter paper (Whatman No 42, Maidstone, England) and stored at 4 ̊C for further experiment.

Phytochemical analysis

The Phytochemical screening of Allium sativum, Zingiber officinale, Capsicum annuum and Azadirachta indica aqueous extract were subjected to qualitative test for the identification of various phytochemical constituents as per standard procedures. The screening was carried out to discover the significant bioactive components such as tannins, saponins, flavonoids, phenols, terpenoids, alkaloids, glycosides, cardiac glycosides, coumarins and steroids ^[8-10].

Gas chromatography- mass spectrometry (GC-MS) analysis

The main phytocomponents of Allium sativum, Zingiber officinale, Capsicum annuum and Azadirachta indica aqueous extract were identified by using GC-MS detection system. The samples were suspended with ethanol and subject to GC-MS analysis. Elucidation of phytocomponents was assayed by comparison of their retention times and mass with their regular authentic standard spectra using computer searches in NIST0. L and Wley7n.l libraries.

Insecticidal activity

The insecticidal activity was evaluated. Twelve Tetranychus urticae were put into a 500 ml glass bottle and kept in the laboratory at 28 ± 1°C, 58 ± 5°% RH (12 h light cycle) and 25.5 ± 1°C, 45 ± 5% RH (12 h dark cycle) for 72 h. Different Ratio of Sample Extraction diluted in Distilled water were tested on T. urticae. The extract was applied to filter paper (Whatman number 1, cut into 7 cm diameter) and immediately introduced into a glass bottle and then sealed. For the control group, the insects were placed in the glass bottles under the same condition but without addition of extraction. Each ratio and control was replicated three times ^[11]. Insect Mortality was determined by observing the recovery of immobilized insects in 24 h intervals up to 72 h. When no antennal or leg movements were observed, insects were considered dead. One synthetic pesticide PROPARGITE is used as control weighed to achieve the appropriate concentrations and was applied according to manufacturer’s directions. Percentage of mortality of T. urticae was observed and overall mortality rate was calculated after 48 hrs using the Abbott’s formula.

Results

Phytochemical screening

Phytochemical screening of sample extract of Allium sativum, Zingiber officinale, Capsicum annuum and Azadirachta indica confirmed the presence and absence of alkaloids, flavonoids, saponin, phenol, steroids, glycosides, Phlobactin, Coumarins, Anthraquinone, Leucoanthocyanin, Triterpenoids and Carbohydrate in individual sample. The negative sign depicted the absence of secondary metabolites (Table 1).

Table 1. Phytochemical screening of aqueous extracts of Allium sativum, Zingiber officinale, Capsicum annuum and Azadirachta indica.

GC-MS Analysis

The presence of biologically active compounds from the ethanol extract of Allium sativum, Zingiber officinale, Capsicum annuum and Azadirachta indica were evaluated by conducting GC-MS analysis ^[12]. The principal active compounds, molecular weight (g/mol, M.W), Molecular Formula (M.F.), Retention time (R.T.) and Peak area (%) are presented in Table 2. The result of GC-MS analysis of the extracts led to the determination of several biological compounds (Table 2).

Table 2: GCMS analysis of aqueous extracts of Allium sativum, Zingiber officinale, Capsicum annuum and Azadirachta indica

Insecticidal activity

The insecticidal bioassay of Allium sativum, Zingiber officinale, Capsicum annuum and Azadirachta indica showed a strong activity against T. urticae within 24 hours ^[13]. At equal ration of all the 4 samples the extract produced 90% mortality after 72 h. The Allium sativum alone showed 58.3% mortality after 72 h. The Zingiber officinale showed 46.7% mortality at 72 h. The Azadirachta indica showed 83% mortality at 72 h ^[14]. The Capsicum annuum showed 72% mortality at 72 h. The synthetic pesticide showed 100% mortality after 24 h and 48 h. Both Sample extract and pesticides reached 100% mortality at 72 h. The negative control showed no activity except at 72 h. The Insecticidal activity of sample extraction against T. urticae is shown below at (Table 3).

Conclusion

This study demonstrated that sample extracted from Allium sativum, Zingiber officinale, Capsicum annuum and Azadirachta indica was toxic to mites Tetranychus urticae. Therefore, it could be used as an alternative strategy for Tetranychus urticae control and as a substitute for synthetic pesticides. However further studies are necessary to elucidate the mode of action and the environmental impact and development of formulations to improve the insecticidal efficacy. This would benefit agricultural sector of developing countries as these samples are readily available and biodegradable.

Acknowledgement

We thank the host institution Dr. N.G.P Arts and Science College, Management for rendering all the facilities and financial support through seed money (Communication number: DrNGPASC 2020-21 BS076.)

The authors acknowledge the use of instrumentation and infrastructure facilities provided by DST-FIST and DBT-Star college scheme, Ministry of science and Technology, Govt. of India for the successful completion of project dissertation.

References

1. Yao Y, et al. Isolation and characterization of insecticidal activity of (Z)‐asarone from Acorus calamus L. Insect Sci. 2008;15:229-236.

   [Crossref] [Google Scholar]

2. Padmaja PG, et al. Efficacy of certain plant oils on the American bollworm Helicoverpa armigera Hübner. Pestic Res J. 2000;12:107-111.

   [Google Scholar]

3. Baskar K, et al. Antifeedant, larvicidal and pupicidal activities of Atalantia monophylla (L) Correa against Helicoverpa armigera Hubner (Lepidoptera: Noctuidae). Chemosphere. 2009;75:355-359.

   [Crossref] [Google Scholar] [Pubmed]

4. Wickramananda IR, et al. Insecticidal activity of leaf extracts of neem (Azadirachta indica A. Juss.). Trop Agric Res. 1998;10:282-290.

   [Google Scholar]

5. Plata-Rueda A, et al. Insecticidal activity of garlic essential oil and their constituents against the mealworm beetle, Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae). Sci Rep. 2017;7:1-1.

   [Crossref] [Google Scholar] [Pubmed]

6. Okonkwo Co, et al. Insecticidal potentials of some selected plants. J Chem Pharma Resear. 2013;5:370-376.

   [Google Scholar]

7. Nesel A, et al. Testing the insecticidal potential of chili pepper (Capsicum frutescens) fruit extract against termites (Coptotermes gestroi). Bio 182. Biotechnol. 2016.

   [Crossref]

8. Ahmed M, et al. Insecticidal activity and biochemical composition of Citrullus colocynthis, Cannabis indica and Artemisia argyi extracts against cabbage aphid (Brevicoryne brassicae L.). Sci Rep. 2020;10:1-0.

   [Crossref] [Google Scholar] [Pubmed]

9. Silva CG, et al. Insecticidal activity of the ethanolic extract from Croton species against Plutella xylostella L.(Lepidoptera: Plutellidae). Rev Fac Nac Agron Medellin. 2018;71:8543-8551.

   [Crossref] [Google Scholar]

10. Jahan F, et al. Fumigant toxicity and nymph production deterrence effect of five essential oils on adults of the cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae). J Essent Oil-Bear Plants. 2016;19:140-147.

    [Crossref] [Google Scholar]

11. Cerda H, et al. Effects of aqueous extracts from amazon plants on Plutella xylostella (Lepidoptera: Plutellidae) and Brevicoryne brassicae (Homoptera: Aphididae) in laboratory, semifield, and field trials. J Insect Sci. 2019;19:8.

    [Crossref] [Google Scholar] [Pubmed]

12. Karimabad MN, et al. Effect of Citrullus colocynthis extract on glycated hemoglobin formation (in vitro). Eurasian J Med. 2020;52:47.

    [Crossref] [Google Scholar] [Pubmed]

13. Jankowska B, et al. Efficacy of aqueous extracts of black alder (Alnus glutinosa Gaertn.) and black elderberry (Sambucus nigra L.) in reducing the occurrence of Phyllotreta spp., some lepidopteran pests and diamondback moth parasitoids on white cabbage. Pol J Entomol. 2016;85:377.

    [Crossref] [Google Scholar]

14. Abbott WS. A method of computing effectiveness of an insecticide. J Econ Entomol. 1925; 18:265-67.

    [Crossref] [Google Scholar]